The present invention relates to a knife apparatus including a knife handle or grip having a C-shaped cross-section defining a groove or a channel extending longitudinally thereof and a slider having a blade secured thereto and slidably received by the channel so that the blade can be withdrawn or projected bit by bit outwardly as the knife edge thereof wears out.
In the knife apparatus of the type described above, it has been hitherto known that a series or notches are formed in the knife handle or grip on the one hand, while a V-shaped spring member is mounted on the blade holder on the other hand, whereby the slider and hence the blade are securely held by the knife handle through the mutual engagement of the V-shaped spring and the notch. When the slider is moved to project the blade outwardly, the V-shaped spring is yieldably deformed to disengage from the notch. Such conventional structure is, however, disadvantageous in that the blade cannot be securely held by the knife handle or grip at the indexed position since the locked or latched state of the slider is assured only by the resiliency of the V-shaped spring member. Consequently, there may arise a danger of the blade tottering or rattling particularly in the applications where a relatively great cutting force is required. Of course, more positive locking of the slider as well as the blade to the knife handle may be attained by using a spring member having a correspondingly increased spring force. However, by doing so, the force required for smoothly sliding the slider is increased inconveniently.
To avoid this problem, there have been proposed various knife apparatus having means for releasably but forcibly keeping the V-shaped spring in engagement with the notch. These means are, however, constituted by a large number of parts of different materials and hence difficult to produce and assemble, incurring inconveniently a rise of production cost of the knife apparatus.